1. Field of Invention
The present invention relates to an exercise device, and more specifically to increasing the effectiveness of abdominal muscle exercises by selectively providing a stable or non-stable platform.
2. Description of the Related Art
Exercise devices that provide a platform for supporting the body in exercising various muscle groups have had the ability to produce instability through the use of a curved or domed surface, to provide instability in one direction or in all directions.
For example, U.S. Pat. No. 1,497,243 to Martin provides a foot exerciser with a rocker bottom on one side and, on the opposite side, two concave foot supporting surfaces divided by a ridge. The user places his feet within the concave foot supporting surfaces; and the feet are separated by the ridge. From that position, the device provides an unstable platform to exercise the feet and lower legs. However, Martin's device cannot be transitioned into a stable exercise platform and cannot be used to exercise other muscle groups, due to its inherent design limitations and teachings.
What is needed and not yet provided in the art, is an exercise device that can exercise upper body, lower body, and abdominal muscle groups, while selectively providing a stable and unstable exercise platform.